Strange Char on LCD HD44780+Pcf8574

[andmattia]

Hi

I use an LCD HD44780 + Pcf8574 in my raspi and i write data via C# code. All works fine but in some case display show strange char. If i restart application it works fine but after some pressure it happens again.

I read this issue is related to freq that arduino solve with wire.setClock.

I try to set
dtparam=i2c_baudrate=190000 (-> 95Khz)
but if remove my thread sleep LCD show strange char

Any idea?

[FTrevorGowen]

Hi

I use an LCD HD44780 + Pcf8574 in my raspi and i write data via C# code. All works fine but in some case display show strange char. If i restart application it works fine but after some pressure it happens again.

I read this issue is related to freq that arduino solve with wire.setClock.

I try to set
dtparam=i2c_baudrate=190000 (-> 95Khz)
but if remove my thread sleep LCD show strange char

Any idea?

What "E-strobe" timings are in use? You may be falling foul of this known issue (esp. w.r.t. PCF8574 based display interfaces):
http://www.cpmspectrepi.uk/raspberry_pi ... gData.html
Trev.

[andmattia]

Hi Trev

thanks for you reply but how can I check this timing?

In my c# app I doesn't set nothing. I use this sketch
https://docs.microsoft.com/en-us/dotnet ... cd-display

[FTrevorGowen]

Hi Trev

thanks for you reply but how can I check this timing?

In my c# app I doesn't set nothing. I use this sketch
https://docs.microsoft.com/en-us/dotnet ... cd-display

Sorry I don't use C# so can't comment further however I would expect the timings to be observable in the source code if you have access to that. If you post what may be the relevant parts here within code tags someone else may be able to advise you better.
Trev.

[andmattia]

Ok

I try to look to source code on gitHub

thanks for your suggestion